From DE 11 2007 002 377 T5 there is known a vibration damper with a vibration damper tube and there is provided an external module tube in which an additional valve arrangement is received. The module tube extends perpendicular to the vibration damper tube, and the flange for connecting the module tube to the vibration damper tube is formed by the module tube itself.
From DE 11 2008 001 980 T5 there is known a vibration damper with a vibration damper tube and with an external module tube in which a valve body arrangement is received. Between the vibration damper tube and the module tube are situated transfer rings, which form a flange between the two tubes, said flange being retained by the module tube on the vibration damper tube. Through the transfer rings there are formed fluid ducts in order to connect the valve body arrangement in the external module tube to the vibration damper tube. The maximum possible spacing between the module tube and the vibration damper tube here is structurally limited by the design of the transfer rings.
The connection between the module tube and the vibration damper tube must play a mechanical retaining role, besides the fluidic connection role. Because of the heavy dynamic loading of a vibration damper tube, great mechanical strength of the module tube on the vibration damper tube is required, and if the spacing between the module tube and the vibration damper tube needs to be increased, for example, for design reasons, then the flange connection between the module tube and the vibration damper tube can no longer be formed only by transfer rings, since these are not sufficiently mechanically loadable.
Although a flange can be made from a metallic material affording a good strength between the module tube and the vibration damper tube, especially when the tubes are welded to the flange, a flange made from a solid metallic material for example can quickly have a large weight. Especially when vibration damper tubes are used as unsprung masses on a vehicle it is important to accomplish a low weight of the vibration damper. A flange made from a plastic material would be lighter, but it would not achieve the required strength, and the module tube would not be mounted with adequate mechanical strength on the vibration damper tube.
For example, if a flange is made of a solid metallic material, the further problem arises of the sealing of the fluid ducts to the tube bodies. The fluid ducts must pass through the flange and be brought into connection with openings which are made in the vibration damper tube and in the module tube. If the connection between the flange and the tubes is formed by a welded connection, the difficulty arises of the seal between the fluid ducts in the flange and the outside of the tubes.
By a combination of a plastic body, in which at least one fluid duct is formed, and by additional connection elements the weight of a flange can be reduced, although the design and especially the mounting of the flange can be made more difficult, even with higher. For example, DE 103 55 151 A1 shows a flange for connecting a vibration damper tube to a module tube, wherein a plastic body is clamped between the two tubes, and then two side connection elements of a metal material must be welded onto the outside of the tubes. This requires a costly welding device.
DE 10 2004 034 725 A1 shows another variant of a flange with a connection piece and with a carrier, wherein the carrier forms a connection element of H shape. To produce the H-shaped connection element, several stamping and bending operations and further welding processes are needed, so that the flange formed in this way has a costly fabrication.
Finally, DE 195 27 849 C1 shows a flange for connecting a vibration damper tube to an external module tube of a vibration damper, wherein a sleeve-like transition body with a respective funnel-shaped opening to the module tube and vibration damper tube is provided. The transition body has to be made in a costly manner by a forming process and the contact surfaces of the transition body must be adapted to the envelope surfaces of the tubes. While this produces a connection element which can be welded onto the tubes, the plastic element to be used in the transition body, known as a support body, is designed as an individual part and it must be installed in the transition body after the latter has already been welded onto the module tube, for example. Consequently, the welding processes have to be interrupted by the inserting of the plastic body, making the mounting of the flange more difficult.